The present invention relates to a method of medium access period allocation for a shared medium networks, and more particularly, to a method of medium access period allocation and a wireless communication system accessing overlapped, partially overlapped or non-overlapped radio frequencies by at least two wireless communication devices.
When a plurality of wireless communication modules, e.g. wireless local area network (WLAN), Bluetooth and Long Term Evolution (LTE) systems, operates in a time-division multiplexing manner, a Network Allocation Vector (NAV) as a virtual carrier sense mechanism is utilized by the WLAN module(s) to reserve a period of time, so as to prevent contentions from its counterparty of WLAN modules. The NAV could be triggered by a Clear to Send to Self (CTS2Self) signal, and comprises timing information to indicate duration that medium will be considered as busy in a WLAN, such that the wireless communication module may consider this duration information of the NAV as a period for its transmission or reception.
However, if there are other WLAN devices which have already reserved the medium in other manner or pattern, duration of medium reservation may not be adequate for the other wireless communication modules to finish its transmission or reception. Please refer to FIG. 1, which illustrates a conventionally schematic diagram of CTS2Self transmissions of WLAN communication devices. As shown in FIG. 1, there are a first wireless communication device utilizing the Bluetooth module and a WLAN module and a second wireless communication device utilizing the WLAN module. The WLAN module and the Bluetooth module of the first wireless communication device operate in a time-division manner. In a precluded time-slotting pattern, the WLAN module of the first wireless communication device operates for a WLAN traffic in a period t1 after the Bluetooth module has completed a Bluetooth traffic. After finishing the WLAN traffic and before ending the precluded time slot (i.e. the period t1), if the second wireless communication device transmit a CTS2Self signal to reserve the medium in another period t2, the first wireless communication device is not able to reserve the medium for a period of time to stop the traffic from its counterparty and allocate this duration for the Bluetooth operation. It is because the NAV has already been reserved by the second wireless communication device in the period t2. Accordingly, the subsequent Bluetooth traffic of the Bluetooth module may potentially collide with another WLAN traffic being sent from the AP to the first wireless communication device. Thus, the first wireless communication device may fail to protect its WLAN traffic due to the consequence of inadequate duration allocation of the NAV from the second wireless communication device.
Therefore, it is essential to provide a resolution for medium reservation to wireless communication system to operate collaboratively in the scenario of coexistence of at least two wireless communication devices.